In laundry applications, silicone oils are commonly used in rinse conditioners formulation to bring additional benefit to the consumer such as a better sensory, antiwrinkle properties and ease of ironing. Materials of this type reduce the level of wrinkling by lubricating the fabric fibres, thereby lowering the fibre friction thus assisting the fabric in recovering from its wrinkled state. Similarly, an ease of iron effect is obtained by reducing the friction between the sole of the iron and the fabric surface. The usual kind of silicone is a polydimethyl siloxane (PDMS) or an aminosilicone, usually in emulsion form and is present at about 5% in the formulation. However, at present, it is difficult to deliver silicones from the main wash.
A mere silicone emulsion, e.g. stabilized with a non-ionic/anionic surfactant system does not show any deposition because of the lack of affinity of the silicone with the cotton surface. One way to improve the silicone uptake on the fabric is to emulsify with a cationic surfactant, as used in conventional rinse conditioner. In that case the positively charged silicone droplets interact with the mildly anionic cotton surface to form a coalesced film at the cotton surface. However, in main wash products cationic silicone emulsions cannot be used because the cationic sites are immediately neutralized by the surrounding anionic surfactant, causing the emulsion to collapse. This results in the partial depletion of the available anionic surfactant and consequently in a decrease of the cleansing efficiency. Moreover, if any silicone deposits at all on the cotton, its distribution is extremely heterogeneous.
The applicants have now found that certain silicone-containing graft or block cationic copolymers, when used as delivery aids in a washing composition, produce silicone emulsions that remain stable in presence of anionic surfactant and lead to high silicone deposition efficiency on a washing process.